Fabrication and supercapacitive properties of a thick electrode of carbon nanotube-RuO₂ core-shell hybrid material with a high RuO₂ loading

A core-shell hybrid material of amorphous hydrous RuO₂-coated carbon nanotubes (CNT-RuO₂) with a RuO₂ loading as high as 82.4wt% was prepared by a solution method using RuCl₃ and NaHCO₃ aqueous solutions. The effect of preparation conditions, especially the dripping speed of the NaHCO₃ solution, on the formation of the core-shell structure was investigated, and the corresponding mechanism was discussed. Supercapacitive properties of the CNT-RuO₂ and amorphous hydrous RuO₂ electrodes with a thickness of over 200μm were studied and the crucial factors to govern their rate capability were analyzed. For the thick CNT-RuO₂ electrode, a comparison of its specific capacitance before and after subtracting the effect of the voltage drop of discharge curves caused by the inner resistance of the CNT-RuO₂ symmetrical supercapacitor indicates that electronic conductivity is more important than proton diffusion in determining its rate capability.